Hand-held power tool

ABSTRACT

The invention relates to a hand-held power tool having a drive motor and a striking mechanism for the rotating or impact drive of a tool, which is accommodated in a tool holder. A transmission gearing and a torque clutch are disposed in the transmission path between the drive motor and the tool holder in order to limit the transferable torque. A threshold torque can be set in the torque clutch.

The invention relates to a hand-held power tool that can be used as arotary hammer and as a drill and is equipped with a drive motor and animpact mechanism for driving a tool in a rotating and hammering modeand/or in an impact mode.

PRIOR ART

DE 10 2005 047 600 A1 describes a hand-held power tool embodied in theform of a rotary hammer that can be used in various operating modes. Onthe one hand, it can be operated as a rotary hammer in which the drivemotion of the drive motor can be transmitted to the drill chuck holdingthe tool via a rotary drive mechanism that can be switched on and offand via an impact mechanism. If only the impact mechanism is active, butnot the rotary drive mechanism, then the rotary hammer is in chiselmode. But if both the rotary drive mechanism and impact mechanism areactivated, then the rotary hammer is operated in impact drill mode. Inanother switch configuration, the impact mechanism is deactivated andonly the rotary drive mechanism is active so that the rotary hammer isoperated in drill mode.

There are also known hand-held power tools that are equipped with atorque-limiting unit that assumes the function of an overload clutch inorder to interrupt the flow of force between the motor output and thedriving element of the tool if the transmitted torque exceeds anoverload torque. A hand-held power tool of this kind that is embodied inthe form of a cordless screwdriver is described for example in DE 102004 058 809 A1. The torque-limiting unit can be used to drive screwswith a uniform torque.

DISCLOSURE OF THE INVENTION

Based on this prior art, the object of the invention is to provide ahand-held power tool that is equipped as a rotary hammer with anadditional operating functionality.

This object is attained according to the invention by means of thedefining characteristics of claim 1. Suitable modifications aredisclosed in the dependent claims.

The hand-held power tool according to the invention can be used both asa rotary hammer and as a drill and is equipped with a drive motor and animpact mechanism. The rotary drive mechanism and the impact mechanismcan advantageously be switched on and off to enable implementation ofvarious functions. For example, when the rotary drive mechanism isdeactivated and only the impact mechanism is active, it is possible tooperate in a chisel mode. The rotary hammer function is achieved byadditionally activating the rotary drive mechanism When the impactmechanism is switched off, the hand-held power tool is in drill-onlymode.

In the hand-held power tool according to the invention, a reduction gearand a torque clutch for limiting the transmissible torque are situatedin the transmission path between the drive motor and the tool holder inwhich the tool is accommodated. Ideally, the torque clutch should beswitchable between an operative position and an inoperative position inwhich the torque limitation is deactivated. It is either possible tomechanically bypass the reduction gear so that the reduction gear canalso be switched between an inoperative position and an operativeposition and/or it is possible to set different transmission ratios inthe reduction gear. In the operative position or with a correspondinglyset transmission ratio, the reduction gear permits the hand-held powertool to be operated as a rotary hammer with a reduced speed incomparison to the drill-only mode. The torque clutch assures that thetransmitted torque does not exceed a threshold torque in screwdrivingmode. This threshold torque is preferably adjustable; it is possible,for example, for at least two, but possibly more, torque stages to beprovided or for there to be an infinitely variable adjustment of thethreshold torque.

In addition to the rotary hammer mode, drill mode, and chisel mode, itis thus also possible for there to be a screwdriving mode in which thereduction gear reduces the high-speed drive motion of the drive motor toa lower-speed rotary motion suitable for the screwdriving functionality;simultaneously, through activation of the torque clutch, it is possibleto set a maximum permissible torque. The activation of the torque clutchis optional; if need be, it can also be omitted in the screwdriver modeor drill mode so that there is no torque limitation.

According to a preferred embodiment, the drive motor, the reductiongear, the impact mechanism, and the torque clutch are situated one afteranother and flush with one another in a line, thus assuring anadvantageous transmission of force from the drive motor via theintermediate units to the tool holder with the tool contained therein.

According to a first preferred embodiment, the torque clutch is situatedbetween the impact mechanism and the tool holder. According to a secondpreferred embodiment, it is also possible to position the torque clutchbefore the impact mechanism and the tool holder. In both cases, thereduction gear is suitably situated immediately at the output side ofthe drive motor and before the impact mechanism and torque clutch.

In a preferred embodiment, the reduction gear is embodied in the form ofa planetary gear that advantageously has at least two switchablereduction ratios. Either all of the planetary stages of the planetarygear are operational to permit a sharply reduced transmission of therotary drive motion of the drive motor to the tool for the screwdrivingmode or one gear of the planetary gear increases the drive motion of thedrive motor to a speed that enables a drill mode.

In another advantageous embodiment, the hand-held power tool is equippedwith a battery pack to supply current to the drive motor, which isembodied as electrical. The battery pack is in particular detachablymounted to the housing of the hand-held power tool and can be rechargedas needed in a charging unit.

The impact mechanism by means of which the rotary hammer mode and chiselmode are to be adjusted is either pneumatically or mechanically embodiedand actuated. In either case, the activation of the impact mechanism isoptional.

Other advantages and suitable embodiments can be inferred from theremaining claims, from the description of the figures, and from thedrawings themselves.

DRAWINGS

FIG. 1 shows a hand-held power tool embodied in the form of a rotaryhammer that is equipped with a drive motor and an impact mechanism fordriving a tool in a rotating and hammering mode and is also equippedwith a reduction gear and a torque clutch for limiting the transmissibletorque so that the hand-held power tool can be used as a rotary hammer,a drill, a chisel, and a screwdriver,

FIG. 2 shows a modified embodiment of the hand-held power tool.

In the drawings, components that are the same have been provided withthe same reference numerals.

The hand-held power tool shown in FIG. 1 is a rotary hammer that has ahousing 2 containing an electric drive motor 3 that is provided withcurrent by means of a battery pack 4 at the bottom of the housing. Thebattery pack 4 is detachably mounted to the housing. The electric drivemotor is actuated by means of a manual switch 5.

To improve the maneuvering of the hand-held power tool 1, a secondhandle can be provided on the housing 2.

The housing 2 of the hand-held power tool 1 also contains a planetarygear 6, an impact mechanism 7, and a torque clutch 8. The planetary gear6 is situated immediately at the output side of the electric drive motor3. It is adjoined by the impact mechanism 7 with which the hammering orimpact function is implemented. Adjacent to the impact mechanism 7 isthe torque clutch 8. The torque clutch 8 is connected to the tool holder9 for accommodating a tool 10; for example, the tool holder 9 isembodied in the form of a drill chuck or slit clamping sleeve.

The electric drive motor 3, the planetary gear 6 functioning as areduction gear, the impact mechanism 7, and the rotary clutch arearranged one after another in the housing 2 of the hand-held power tool1 and share a common longitudinal axis that is simultaneously therotation axis of the drive motor and of the tool holder 9 with the tool10. The planetary gear 6 is advantageously provided with different gearstages that can be set by the user. The impact mechanism 7 is embodiedso that it can be switched on and off, as is the torque clutch 8, whichpreferably can be used to set different-level torque thresholds that canbe transmitted between the electric drive motor and the tool holder.

The exemplary embodiment of a hand-held power tool 1 shown in FIG. 2 islargely identical to the one shown in FIG. 1 and for this reason, thereader can refer to the description relating to FIG. 1. What differs,however, is the arrangement of the impact mechanism 7 and torque clutch8. The torque clutch 8 directly adjoins the planetary gear 6, which issituated at the output side of the electric drive motor 3. The torqueclutch 8 is adjoined by the impact mechanism 7 to which the tool holder9 is coupled.

In an alternative embodiment not shown here, the torque clutch 8encompasses the impact mechanism 7.

1-13. (canceled)
 14. A hand-held power tool that is usable as a rotaryhammer and as a drill, comprising: a drive motor: an impact mechanismfor driving a tool of the hand-held power tool in a rotating and/orhammering mode; a tool holder accommodating the tool; and a reductiongear and a torque clutch which limit the transmissible torque beingsituated in a transmission path between the drive motor and tool holder,wherein a torque limitation in the torque clutch can be set.
 15. Thehand-held power tool as recited in claim 14, wherein the drive motor,the reduction gear, the impact mechanism, and the torque clutch aresituated one after another and flush with one another in a line.
 16. Thehand-held power tool as recited in claim 14, wherein the torque clutchis situated between the impact mechanism and the tool holder.
 17. Thehand-held power tool as recited in claim 15, wherein the torque clutchis situated between the impact mechanism and the tool holder.
 18. Thehand-held power tool as recited in claim 14, wherein the impactmechanism is situated between the torque clutch and the tool holder. 17.The hand-held power tool as recited in claim 15, wherein the impactmechanism is situated between the torque clutch and the tool holder. 20.The hand-held power tool as recited in claim 16, wherein the reductiongear is situated immediately at the output side of the drive motor. 21.The hand-held power tool as recited in claim 18, wherein the reductiongear is situated immediately at the output side of the drive motor. 22.The hand-held power tool as recited in claim 20, wherein the reductiongear is a planetary gear.
 23. The hand-held power tool as recited inclaim 21, wherein the reduction gear is a planetary gear.
 24. Thehand-held power tool as recited in claim 14, wherein the hand-held powertool is equipped with a battery pack which supplies current to theelectric drive motor.
 25. The hand-held power tool as recited in claim15, wherein the hand-held power tool is equipped with a battery packwhich supplies current to the electric drive motor.
 26. The hand-heldpower tool as recited in claim 14, wherein the impact mechanism ismechanically actuated.
 27. The hand-held power tool as recited in claim15, wherein the impact mechanism is mechanically actuated.
 28. Thehand-held power tool as recited in claim 14, wherein the impactmechanism is pneumatically actuated.
 29. The hand-held power tool asrecited in claim 15, wherein the impact mechanism is pneumaticallyactuated.
 30. The hand-held power tool as recited in claim 14, whereinit is possible to set at least two torque stages in the torque clutchwhen it is in an operative position.
 31. The hand-held power tool asrecited in claim 14, wherein the tool holder is embodied in the form ofa drill chuck.
 32. The hand-held power tool as recited in claim 14,wherein the tool holder is embodied in the form of a slit clampingsleeve.
 33. The hand-held power tool as recited in claim 14, wherein itis possible to switch the torque clutch between an operative positionand an inoperative position in which the torque limitation isdeactivated in the inoperative position.